As the global precision manufacturing industry continues to upgrade toward miniaturization, high precision, and high durability, Metal Injection Molding (MIM) has become the mainstream forming process in high-end sectors including consumer electronics, medical devices, and the automotive industry, with its core strength of mass-producing precision parts with complex geometries. In the back-end supporting process of MIM, a surface modification technology is continuously expanding the performance boundaries of precision parts — Diamond-Like Carbon (DLC) coating.

I. What is DLC Coating?

DLC (Diamond-Like Carbon) is an amorphous carbon-based thin film material. Its carbon atomic structure integrates both the sp³ hybrid bonds of diamond and the sp² hybrid bonds of graphite. This unique structure endows it with the core advantages of both materials: it delivers ultra-high hardness and excellent corrosion resistance close to diamond, along with the ultra-low friction coefficient and inherent self-lubricating properties of graphite.

Simply put, DLC coating acts as a high-performance protective armor tailor-made for MIM precision components. It comprehensively upgrades the surface performance of parts without altering their basic form, forming accuracy, and structural design.

II. Core Compatibility Advantages of DLC Coating for MIM

The MIM process focuses on the large-scale manufacturing of small, complex, high-precision metal structural parts, with stringent requirements for the temperature, film uniformity, and dimensional impact of post-treatment processes. The technical characteristics of DLC coating are highly aligned with the high-end demands of MIM parts, enabling performance upgrades while fully retaining the core advantages of the MIM forming process:

1. Low-Temperature Deposition, No Damage to Part Accuracy

The deposition temperature of DLC coating is typically controlled at 70–200℃, a classic low-temperature preparation process. It does not alter the matrix metallographic structure of MIM sintered parts, nor cause dimensional deformation, perfectly matching the high-precision tolerance requirements of MIM ±0.1%~±0.3%.

2. Ultra-Thin and Uniform, Adaptable to Complex Special-Shaped Structures

The thickness of conventional DLC films is only 0.5–3μm. The film is uniform and dense, and can fully cover complex structures common in MIM parts, such as thin walls, micro holes, special-shaped curved surfaces, and undercuts, without affecting assembly dimensions and fitting accuracy.

3. Ultra-High Hardness, Significantly Improved Wear Resistance and Service Life

Conventional DLC can reach a hardness of 2000–3000HV, while high-performance ta-C type DLC can exceed 5000HV at maximum. It can greatly enhance the scratch and wear resistance of MIM parts, effectively solve the problems of wear and insufficient service life of micro moving parts under high-frequency working conditions, and provide long-term performance guarantee for products.

4. Ultra-Low Friction, Self-Lubricating for Friction and Energy Consumption Reduction

DLC has a dry friction coefficient as low as 0.05–0.2 under oil-free lubrication conditions, with excellent self-lubricating properties. It is especially suitable for reciprocating or rotating moving parts manufactured by MIM, such as gears, rotating shafts, and sliders, reducing friction loss and improving running smoothness and stability.

5. Strong Corrosion Resistance, Expanding Application Boundaries

The dense, non-porous DLC film can effectively isolate harsh environments such as acid, alkali, and high humidity, compensating for the anti-corrosion shortcomings of common MIM base materials including low carbon steel and low alloy steel. Meanwhile, it can greatly improve the anti-corrosion performance of mainstream MIM stainless steel base materials such as 316L in harsh salt spray and damp-heat environments, enabling MIM parts to meet the stringent environmental requirements of medical, automotive, outdoor and other sectors.

III. Practical Applications of DLC Coating in the MIM Sector

As the core supporting post-treatment process for MIM parts to achieve high-end and high-performance, DLC coating has been widely applied in multiple high-demand sectors, helping MIM formed parts adapt to more high-end application scenarios:

Conclusion

As precision manufacturing continues to upgrade toward smaller sizes, higher precision, and harsher working conditions, the combination of MIM and DLC coating is becoming the “golden partner” for high-end components. While fully retaining the core advantages of the MIM process in large-scale production, high precision, and complex structure forming, DLC coating further breaks through the performance limits of MIM parts, helping products achieve comprehensive upgrades in durability, reliability, and appearance texture. It provides strong technical support for product innovation and upgrading in consumer electronics, medical, automotive, and other industries.

In the future, with the continuous in-depth integration of coating technology and MIM process, DLC will further unlock the performance potential of precision components and become an indispensable supporting key technology in the field of high-end MIM manufacturing.